Interpretive Summary: A field experiment evaluating pre-plant swine effluent application methods was conducted to measure greenhouse gas (CO2, CH4, and N2O) emissions from a no-till corn grain production. The treatments included a control, an inorganic fertilizer treatment receiving 179 kg N ha-1 as urea ammonium nitrate (UAN), and three effluent application methods that received a target rate of 200 kg N ha-1. The effluent treatments included: surface application, direct injection, and application in combination with soil aeration. Gas emission measurements were initiated after application and collected throughout the 2007 and 2008 growing seasons using a vented chamber technique. There were no significant differences in CO2 losses, which averaged 738 and 718 g CO2 m-2 in 2007 and 2008, respectively. Placement of effluent below the soil surface by injection or aeration resulted in elevated CH4 emission compared to the control. Injection method consistently emitted the largest amount of CH4 with emissions of 0.26 and 0.80 g CH4 m-2, in 2007 and 2008, respectively. In 2007, N2O emissions were similar for the UAN, surface effluent, and aeration effluent treatments; emitting an average of 0.72, g N2O m-2. In contrast, the injection treatment emitted 0.47 g N2O m-2. In 2008, this trend was reversed with the injection treatment emitting 0.82 g N2O m-2 and the remaining N source treatments emitting an average of 0.36 g N2O m-2. These differences between years likely resulted from differences in rainfall distribution. These results demonstrate that climatic conditions and application method need consideration when evaluating the impact of liquid manure management on greenhouse gas emissions.

Technical Abstract:
Greenhouse gas (CO2, CH4, and N2O) emissions were measured from a field experiment evaluating pre-plant swine effluent application methods for no-till corn grain production. The treatments included a control, an inorganic fertilizer treatment receiving 179 kg N ha-1 as urea ammonium nitrate (UAN), and three effluent application methods that received a target rate of 200 kg N ha-1. The effluent treatments included: surface application, direct injection, and application in combination with soil aeration. Gas emission measurements were initiated after application and collected throughout the 2007 and 2008 growing seasons using a vented chamber technique. There were no significant differences in CO2 losses, which averaged 738 and 718 g CO2 m-2 in 2007 and 2008, respectively. Placement of effluent below the soil surface by injection or aeration resulted in elevated CH4 emission compared to the control. Injection consistently emitted the largest amount of CH4 with emissions of 0.26 and 0.80 g CH4 m-2, in 2007 and 2008, respectively. In 2007, N2O emissions were similar for the UAN, surface effluent, and aeration effluent treatments; emitting an average of 0.72, g N2O m-2. In contrast, the injection treatment emitted 0.47 g N2O m-2. In 2008, this trend was reversed with the injection treatment emitting 0.82 g N2O m-2 and the remaining N source treatments emitting an average of 0.36 g N2O m-2. These differences between years likely resulted from differences in rainfall distribution. These results demonstrate that climatic conditions and application method need consideration when evaluating the impact of liquid manure management on greenhouse gas emissions.